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Biomedical subjects

F G Jennekens

Publications and source records attributed to F G Jennekens.

At least 91 records · Page 5Linked to original sources
PubMed1988

Estimation of the number of motor units based on macro-EMG.

The technique of the macro-EMG was used to estimate the number of motor units in the tibialis anterior muscles of healthy subjects in a wide range of ages, and of patients with myasthenia gravis and patients with amyotrophic lateral sclerosis or spinal muscular atrophy. The results obtained suggest a decrease in the number of motor units in the tibialis anterior muscle with increasing age in normal subjects. In myasthenic patients the motor unit count was within the normal range for their age group. Patients with motor neuron disorders on the average had a very low number of motor units.

Adult↗
PubMed1988

Light- and electron-microscopical study of phosphoprotein B-50 following denervation and reinnervation of the rat soleus muscle.

The neuron-specific phosphoprotein B-50 was originally identified as a phosphoprotein in synaptic plasma membranes isolated from adult brain tissue. In this paper we study the reinnervation of the soleus muscle, a target muscle of sciatic nerve axons, using affinity-purified anti-B-50 antibodies. Light-microscopical evaluation of the reinnervation process revealed that the period of muscle fiber reinnervation corresponds closely with the time in which high B-50 immunoreactivity was observed in the nerve fibers that invade the muscle and in the newly formed neuromuscular junctions. Upon completion of reinnervation, B-50 immunoreactivity decreased. In the newly innervating terminals, B-50 was associated with presynaptic vesicular structures and with the presynaptic plasma membrane. In intact mature neuromuscular junctions, virtually no B-50 immunoreactivity could be detected with either light- or electron-microscopic procedures. These observations corroborate the association of high levels of B-50/GAP43 during axon outgrowth and support the concept that B-50 may be a key molecule in the reconstruction of axonal structures. We also observed an unexpected transient increase in B-50 immunoreactivity in the degenerating neuromuscular junctions. This observation cannot be explained in terms of increased neuronal synthesis of B-50, since the degenerating axon processes have been completely disconnected from their cell bodies. Thus, our evidence implies that a rise of B-50 immunoreactivity can be associated with stages of neuronal degeneration as well as with those of neuronal differentiation and axon outgrowth.

Acetylcholinesterase↗
PubMed1987

Evaluation of cis-diamminedichloroplatinum (II) (cisplatin) neurotoxicity in rats.

Cisplatin neurotoxicity was studied in rats by using electrophysiological and functional tests. The drug was injected intraperitoneally two times a week (1 mg/kg) up to a cumulative dose of 19.0 mg/kg body wt. At this dose the H-reflex-related sensory nerve conduction velocity was reduced. After cessation of drug administration, the H-reflex-related sensory nerve conduction velocity slowly improved. The motor nerve conduction velocity remained unaffected throughout the intoxication period and concentric needle investigation showed no signs of denervation. In addition, the sensorimotor response to a noxious stimulus presented locally to the foot sole was not affected by the cisplatin treatment. It is concluded that measurement of H-reflex-related sensory nerve conduction velocity is a useful and accurate tool in the evaluation of cisplatin neurotoxicity in rats.

Animals↗
PubMed1987

Early effect of an ACTH4-9 analog (Org.2766) on regenerative sprouting demonstrated by the use of neurofilament-binding antibodies isolated from a serum raised by alpha-MSH immunization.

Antibodies binding to the 150 kDa neurofilament protein NF150 have been purified from a serum raised by immunizing a rabbit with alpha-MSH. The NF150-binding antibodies were purified by affinity chromatography on a column of cytoskeletal proteins coupled to CNBr-activated Sepharose-4B. Immunocytochemical application of these antibodies, followed by a FITC-coupled second antibody, labels axons in intact and regenerating nerves and provides a means of identifying and counting small regenerating sprouts from 48 h after nerve crush. We have been able to demonstrate that treatment with the neurotrophic melanocortin analog, Org.2766, increases the number of regenerating axons present in the nerve as early as 72 h after nerve crush.

Adrenocorticotropic Hormone↗
PubMed1987

Org.2766 protects from cisplatin-induced neurotoxicity in rats.

One of the side-effects of the cytotoxic drug, cisplatin, is its neurotoxicity. In rats this neurotoxicity can be measured as a slowing of the H-reflex-related sensory nerve conduction velocity. Concurrent treatment with Org.2766 (an ACTH4-9 analog) prevents this neurotoxic side effect while leaving the antitumor activity of cisplatin unaffected.

Adrenocorticotropic Hormone↗
PubMed1987

The slow channel syndrome. Two new cases.

Two patients are described with a myasthenic syndrome that presented in early adult life. One patient had 2 asymptomatic first degree relatives with similar electrophysiological findings. Both patients had abnormal fatiguability, arm weakness being prominent; neither of them responded to anticholinesterase medication. An abnormal decrement at 3 Hz stimulation was present, and a single stimulus evoked a repetitive response. Electrophysiological studies on biopsied intercostal muscle showed miniature endplate potentials of normal amplitudes but with prolonged rise and decay times. Anticholinesterase staining (Case 1) was not reduced, and showed elongation of some endplates. Ultrastructural studies (Case 2) showed degeneration of junctional folds and diffusely thickened endplate basal lamina. Calcium deposits were not observed and myopathic changes were slight. The findings are consistent with a prolonged open time of the ACh-induced ion channel.

Acetylcholinesterase↗
PubMed1987

A congenital myasthenic disorder with paucity of secondary synaptic clefts: deficiency and altered distribution of acetylcholine receptors.

Congenital myasthenia (CM) constitutes a heterogeneous group of disorders with different underlying defects. The authors investigated a case of CM, presenting with congenital contractures. Endplate studies in the first year of life showed a developmental disorder of postsynaptic membranes. Clinical follow-up demonstrated a beneficial effect of pyridostigmine, resulting in normal motor development. Results of a second biopsy at age 4 are reported in this paper. Microelectrode study showed small Mepp amplitudes, which returned to nearly normal in the presence of neostigmine. In the electronmicroscope the postsynaptic membranes showed a paucity of infoldings, as in the first biopsy. These membranes showed only scanty, patchy enhancement with two different methods for localization of AChR. The extrajunctional membranes showed evidence of local presence of AChR. Our results show a developmental disorder of postsynaptic membranes with a deficiency and altered distribution of AChRs.

Biopsy↗
PubMed1987

Proximal weakness of the extremities as main feature of amyloid myopathy.

Two patients with muscle weakness caused by amyloid myopathy are described. Characteristic features such as pseudohypertrophy and abnormal firmness, and tumours of muscles were absent. It is suggested that muscle weakness in amyloid myopathy is caused by layers of amyloid covering muscle fibres. In middle aged or elderly patients with proximal muscle weakness the diagnosis of amyloid myopathy should be considered.

Aged↗
PubMed1987

Immunohistochemical localization of acetylcholine receptors at human endplates using a monoclonal antibody.

We describe a simple indirect immunohistochemical method for localization of acetylcholine receptors (AChR) in motor endplates at the light and electron microscopic level. This method involves the use of a monoclonal antibody directed against the main immunogenic region (MIR) of AChRs and is applicable to periodate-lysine-paraformaldehyde (PLP)-fixed tissue. We discuss the advantages of this method, as compared with the alpha-bungarotoxin-immunoperoxidase technique, and stress its value for diagnostic investigations of motor point biopsies from patients with neuromuscular transmission disorders.

Adolescent↗
PubMed1986

Characterization of epitopes shared by alpha-melanocyte-stimulating hormone (alpha-MSH) and the 150-kD neurofilament protein (NF150): relationship to neurotrophic sequences.

Immunoblot techniques and immunohistochemistry have been used to investigate epitopes shared by alpha-melanocyte-stimulating hormone (alpha-MSH) and the 150-kD neurofilament protein (NF150). Three anti-alpha-MSH antisera (namely 31H2T, 4394, and M5) from a total of 12 sera were found to react with NF150. The three crossreacting sera are different in their binding properties to peptide fragments related to alpha-MSH, suggesting that at least two distinct epitopes are shared by NF150 and alpha-MSH. The only known sequence common to NF150 and alpha-MSH, the N-terminal Ac-S-Y residues, appears to be essential for binding of sera 31H2T and 4394. However, the binding of antiserum M5 involves other, currently unknown, similarities between NF150 and alpha-MSH. This is shown by the binding of M5 to peptides such as ACTH(4-10), which do not contain the N-terminal Ac-S-Y sequence. Binding of M5 to tobacco mosaic virus coat protein (TMV-coat protein), which is homologous with alpha-MSH and NF150 in its Ac-S-Y residues, was negligible. The peptide structures that are recognized by M5 have previously been shown to exert neurotrophic activity. The data are discussed in the light of the hypothesis that similarity between NF150 and alpha-MSH, as illustrated by binding to M5, may be significant in the neurotrophic activity of MSH-related peptides.

Animals↗
PubMed1986

Alpha-melanocyte-stimulating hormone stimulates the outgrowth of myelinated nerve fibers after peripheral nerve crush.

The effect of alpha-melanocyte-stimulating hormone on peripheral nerve regeneration was studied by monitoring functional recovery and quantifying histologic changes that follow crush lesion of the rat sciatic nerve. The results showed that such treatment of rats with a crushed sciatic nerve resulted in a reduction of the recovery period and in an increase in the number of regenerating nerve fibers.

Animals↗
PubMed1986

The kinase C substrate protein B-50 and axonal regeneration.

As reported previously the prominent protein kinase C substrate protein B-50 is present in growth cones isolated from fetal rat brain and in outgrowing hippocampal neurites. These findings suggest that B-50 plays a role in axonal growth during development of the nervous system. In the present paper the fate of B-50 is investigated in regenerating rat sciatic nerve. Using affinity-purified anti-B-50 antibodies B-50 levels have been compared in crushed and contralateral intact nerves by means of immunoblotting and radioimmunoassay. B-50 levels in the crushed nerve increased 5.3-fold as compared to non-crushed controls. Furthermore, the cellular localization of B-50 has been assessed by immunohistochemistry. Virtually no B-50 immunoreactivity was seen in control nerves, but bright immunofluorescence appeared in regenerating sprouts. Our data are in line with current evidence from several laboratories that B-50 is a member of a small family of growth-associated proteins and support the hypothesis that B-50 is involved in axonal growth.

Animals↗
PubMed1986

Myotonic dystrophy associated with hereditary motor and sensory neuropathy.

Thirteen members of a large family presented with a hereditary motor and sensory neuropathy (HMSN); 8 of them also showed more or less prominent signs of myotonic dystrophy (MyD). There were no cases with MyD alone. The disorder showed segregation with genetic markers for the MyD gene on chromosome 19. This was also true for the 5 subjects in which clinically only HMSN had been detected, 3 of whom were young children. This is the first time that a form of HMSN has been found to be coded for by a gene localized on chromosome 19. The syndrome could be caused by an allelic form of the 'common' MyD gene or by two closely linked genes on chromosome 19.

Adult↗